Arteriovenous Dialysis Access Research Articles

The feasibility of a novel method to remove circumferentially ruptured balloons during ultrasound-guided percutaneous transluminal angioplasty for arteriovenous dialysis access

Objective: Angioplasty balloon rupture is a rare complication during percutaneous transluminal angioplasty (PTA). Conventional approach to retrieve circumferentially ruptured balloons is open surgery. This study examined the feasibility of a novel approach which can remove ruptured balloon during PTA in vascular access. Methods: This retrospective study analyzed 35 patients of a total 6465 patients that underwent ultrasound-guided PTA with a circumferential balloon rupture from February 2016 and August 2023. The patients underwent surgery (Group I, n = 13) or the novel method (Group II, n = 22) for balloon retrieval. Kaplan–Meier curve was used to assess the primary patency rates of the two groups. Result: The total incidence of circumferential balloon rupture was 0.5% in our center. Balloon retrieval was successful in both groups with no complications except one case had an infection in the surgical wound. Kaplan–Meier curve analysis showed that the post-intervention primary patency rates of the two methods were not significantly different ( p > 0.05). There was a significant difference between pre-operation and post-operation brachial arterial flow ( p < 0.001). Conclusion: The feasibility of the novel technique for retrieval of circumferential ruptured balloons during ultrasound-guided PTA is validated. The technique enables less invasive retrieval and continuation of PTA.

The Effect of Dialysis Membranes on Coagulation Activation during Haemodialysis of Maintenance Haemodialysis Patients

Abstract Background Platelets, leukocytes, and the coagulation cascade are activated during hemodialysis. During hemodialysis, systemic anticoagulation is used to prevent clotting of the extracorporeal circuit which may lead either to complete clotting to the degree that prevent blood return to the patient or to a lesser extent can only affect the dialyzer membrane fibers which will decrease the effective surface area and that will decrease the session efficacy Aim of the Work The aim of the current study was to evaluate contact system activation and overall coagulation activation during in vivo hemodialysis in prevalent hemodialysis patients, using current generation dialyzer membranes. A crossover study design allowed assessment of differences among regular dialyzer membranes. Patients and Methods We performed a single-center sequential interventional clinical trial study. Twenty patients older than 18 years and treated with maintenance hemodialysis (>3 months) underwent 2 hemodialysis study sessions at Ain Shams University hospitals dialysis unit. Exclusion criteria were clopidogrel or anticoagulant therapy, active infection, presence of central venous catheter or arteriovenous graft and known vascular access dysfunction. Results The increase of TAT at 240 minutes after dialysis start in our study, irrespective of the dialyzer membrane used, suggests a late-onset threshold for thrombin generation, which is well before the treatment effect of the UFH is expected to have faded. The changes in TAT dynamics are in line with previously published results. Dialysis treatments were standardized except for dialyzer membrane. Hence, the differences between membranes are most likely due to differences in physicochemical characteristics. Whether these differences are clinically meaningful needs further study. Analysis costs and the exploratory set-up of the trial drove the small sample size and design of the study. A more comprehensive evaluation of the coagulation activation over a longer time period of hemodialysis treatment would be of interest. Conclusion Driven by the recent interest in the therapeutic options of specific contact system inhibitors, we aimed to evaluate contact system activation during in vivo he-modialysis. Chronic hemodialysis patients dialyzed through arteriovenous dialysis access show coagulation activation during hemodialysis, marked by increased TAT levels, despite using systemic anticoagulation to prevent macroscopic clotting of the extracorporeal circuit. The increase in thrombin generation markers was not associated with measurable contact system activation. Our results argue against effective contact system activation during hemodialysis and generate the hypothesis that novel specific contact system inhibitors alone might not suffice as anticoagulant treatment during hemodialysis.

Axillary and brachial artery aneurysm associated with a longstanding arteriovenous fistula

Upper extremity true arterial aneurysms are rare and often present as a pulsatile mass with associated pain and paresthesia from peripheral nerve compression, and can lead to acute limb ischemia from thromboembolic sequela. History of arteriovenous dialysis access and immunosuppression after renal transplantation may contribute to the development of true aneurysms.This report describes the management of a patient with end-stage renal disease (ESRD) with multiple left upper extremity dialysis access who presented with an axillary and brachial artery aneurysm.

High Prevalence of Adverse Social Determinants of Health in Dialysis Access Creation Patients in a Safety-Net Setting

Patients receiving dialysis access surgery are often exposed to adverse social determinants of health (SDH) that negatively impact their care. Our goal was to characterize these factors experienced by our arteriovenous dialysis access patients and identify differences in health outcomes based on their SDH. We performed a retrospective cohort study of all patients who underwent dialysis access creation (2017-2021) and were screened for SDH at a clinical visit (using THRIVE survey) implemented at an urban, safety-net hospital institution within one year of access creation. Demographics, procedural details, early postoperative outcomes, survey responses, and referral to our hospital's preventive food pantry were recorded. Univariable analysis and multivariable analyses were performed to assess for associations with key health outcomes. There were 190 patients who responded to the survey within one year of their operation. At least one adverse SDH was identified in 42 (22%) patients. Normalized to number of respondents for each question, adverse SDH identified were difficulty obtaining transportation to medical appointments (18%), food insecurity (16%), difficulty affording utilities (13%), difficulty affording medication (12%), unemployed and seeking employment (9%), unstable housing (7%), difficulty caring for family/friends (6%), and desiring more education (5%). There were 71 (37%) patients who received food pantry referrals. Mean age was 60 years and 38% of patients were female and 64% were Black. More than half of patients (57%) had a tunneled dialysis catheter (TDC) at the time of access creation. Dialysis accesses created were brachiocephalic (39%), brachiobasilic (25%), radiocephalic fistulas (16%), and arteriovenous grafts (14%). Thirty-day emergency department visits, 30-day readmissions, and 90-day mortality occurred in 23%, 21%, and 2%, respectively. On univariable and multivariable analyses, any adverse SDH determined on survey and food pantry referral were not associated with preoperative dialysis through TDCs, receiving non-autogenous dialysis access, 30-day emergency department visits and readmissions, or 90-day mortality. Nearly a quarter of dialysis access surgery patients at a safety-net hospital experienced adverse SDH and more than one-third received a food pantry referral. Most common difficulties experienced include difficulty obtaining transportation to medical appointments, food insecurity, and difficulty paying for utilities and medication. Although there were no differences in postoperative outcomes, the high prevalence of these adverse SDH warrants prioritization of resources in this population to ensure healthy equity and further investigation into their effects on health outcomes.

Contrast Venography Versus Intravenous Ultrasound in Hemodialysis Arteriovenous Access Dysfunction

Contrast Venography Versus Intravenous Ultrasound in Hemodialysis Arteriovenous Access Dysfunction

Comparing Patency Rates of Arteriovenous Dialysis Access following Percutaneous Thrombectomy Using Various Catheter Directed Therapies

Arteriovenous fistulas often require frequent interventions to maintain patency for hemodialysis. Interventions may include open or percutaneous thrombectomy with additional targeted interventions as indicated. We evaluated the primary and cumulative functional patency rates following three unique approaches to percutaneous thrombectomy of thrombosed dialysis access. A retrospective review of 236 unique patients who presented with thrombosed hemodialysis access was analyzed over a period of 4 years from 2016-2020. We analyzed a total of 413 procedures that utilized 3 separate percutaneous thrombectomy devices to assist with restoring patency. The Indigo System CAT-D Aspiration Thrombectomy Catheter (Penumbra; Alameda, CA), the Arrow-Trerotola Rotational Thrombectomy System (Teleflex; Wayne, PA) and the Angiojet Rheolytic Thrombectomy Catheter (Boston Scientific, Marlborough, MA) devices were compared for primary and cumulative functional patency. Primary Patency was defined as time from percutaneous thrombectomy to next intervention (Angioplasty, stenting, repeat thrombectomy). Cumulative functional patency was defined as time from percutaneous thrombectomy to time of access abandonment. Medical record chart review was utilized to determine patency rates. A total of 413 percutaneous thrombectomy procedures were performed. Of the procedures performed, 98 utilized Angiojet, 103 utilized Trerotola, and 212 used Penumbra. Mean primary patency rates in (days) for the devices was as follows: Angiojet (194), Trerotola (204), and Penumbra (107). Mean cumulative functional patency rates (in days) for the devices was as follows: rheolytic thrombectomy (450 days), aspiration thrombectomy (292 days), rotational thrombectomy (475 days). Angiojet vs Penumbra and Trerotola vs Penumbra both showed diminished patency rates when using the Penumbra Catheter that were statistically significant (P<.05) CONCLUSION: All percutaneous thrombectomy approaches do not result in the same primary or cumulative functional patency rates. Approaches with Trerotola and Angiojet resulted in improved primary and cumulative functional patency rates compared to those using Penumbra.

Dialysis Access Evaluation

The vascular lab (VL) provides vital information for dialysis access to guide management. This article discusses the indication, protocol, and diagnostic criteria for the evaluation of arteriovenous fistulas and grafts. An arteriovenous (AV) dialysis access is made by creating a connection between an artery and vein (AV fistula [AVF]) or by interposing a conduit between an artery and a vein (AV graft [AVG]) to provide high flow circuit for hemodialysis. A normal mature AV dialysis access has a thrill or vibration from turbulent flow in the graft or vein. The nomenclatures at our institution for an AVF and AVG are in the Figure 1 A and B diagrams.

Receiver operating characteristic curve analysis of arteriovenous dialysis access flow using ultrasound.

Despite numerous studies investigating the use of ultrasound (US) in assessing arteriovenous fistulas (AVF), there are no universally agreed threshold flow velocities in diagnosing significantly abnormal flow that are useful in predicting thrombotic flow-related dysfunction. This study evaluates a predictive model using receiver operating characteristic curve (ROC) analyses to establish threshold velocities. Five hundred and eleven US scans were analysed. ROC curves were used to determine the optimal threshold time average mean velocity (TAMV), peak systolic velocity (PSV) and end diastolic velocity (EDV) of the brachial artery supplying the AVF in determining the need for intervention or thrombosis within 3months of the scans. Estimated flow volume (FV) ROC was used as an evaluative comparison. There were 356 negative and 155 positive scan results in relation to the need for intervention or thrombosis. Empirical flow velocity parameters of TAMV, EDV and PSV were analysed using ROC curves, yielding an area under the curve (AUC) of 0.95, 0.92 and 0.86, respectively. FV ROC analysis yields a comparative AUC of 0.90. A TAMV cut-off at 48.6cm/s yielded the highest AUC. Subgroup analysis yielded an optimal TAMV cut-off of 45 cm/s for forearm and 49 cm/s for arm AVF. The EDV was also highly predictive of outcomes. PSV has the lowest accuracy. The TAMV of inflow brachial artery to AVF is highly predictive of outcomes of thrombotic flow-related dysfunction. Our study confirms TAMV cut-offs of 45 cm/s for forearm and 49 cm/s for arm AVF. These results require prospective validation.

Vasodilator agents improve hemodialysis vascular access patency: A population-based study from Korea.

Vascular access (VA) failure is an important problem for patients undergoing hemodialysis, and maintaining VA patency is challenging. In this study, we used a nationwide database to investigate the effects of nitrate, as a vasodilator, on VA failure in hemodialysis patients.We investigated the Korean insurance claims data of hemodialysis patients who underwent angioplasty for VA failure between January 2012 and December 2017. The patients were divided into 2 groups: those not receiving vasodilator therapy (controls) and those receiving any vasodilator administration (vasodilator treatment, VDT). The primary endpoint was VA primary patency, defined as the time between arteriovenous dialysis access creation and the first percutaneous transluminal angioplasty (PTA).During the study period, a total of 6350 patients were recruited, 409 (6.4%) patients assigned to the VDT group and 5941 (93.6%) controls. PTA was performed in 998 patients (15.7%), including 8 in the VDT group and 990 controls. The VA site PTA rate was significantly lower in the VDT group (2.0%) than in the control group (16.7%, P < .001). In the subgroup analysis, the patency rates associated with the different vasodilators were similar (P = .736). All vasodilators, except molsidomine, improved the patency rate by approximately 20%.In this large national database study, vasodilator administration was associated with higher VA primary patency, compared with controls, in hemodialysis patients. VDT may have a beneficial effect on maintaining VA patency in patients undergoing hemodialysis.

Abstract No. 545 Effect of multiple patient specific and procedure related factors on patency of dialysis access after declotting procedure

To determine effect of multiple patient specific and procedure related factors on re-thrombosis of arteriovenous dialysis access that underwent declotting procedure by interventional radiology. Consecutive patients that underwent declotting of thrombosed arteriovenous dialysis access were enrolled. Multiple variables including patient’s demographics, comorbidities, and procedure related technical factors were recorded. The effects of these variables on re-thrombosis of the dialysis access during the 12months follow-up period was determined. A total of 111 consecutive patients (age: 61.5 ± 16.9 years, female 47%, male 53%; race: 80% African American, 18% white American, other 2%) were enrolled. Main underlying factors leading to renal failure were determined as DM 13%, HTN 25%, both 41% and other 21%. The access point included AV graft in 78% and AV fistula in 22%. Angiographic/technical declotting was not achieved in 30 (27%) patients at the time of initial declotting procedure. Patients demographic, underlying comorbidities, site or age of the dialysis access was not associated with initially successful angiographic/technical declotting (P > 0.05). In patients with successful declotting (n = 81, 71%), a combination of pharmacologic and mechanical thrombolysis with balloon angioplasty was utilized. 26 (32%) patients had existing vascular stent and in 5 (6%) patients a new stent was deployed. In 9 (11%) patients mechanical thrombectomy device (AngioJet, Argon Cleaner, or Arrow-Trerotola) was used. During the follow-up period (data available in 75 of 81 patients), 27 (36%) patients had re-thrombosis of the access point. The rate of re-thrombosis was significantly higher in AV graft compared to AV fistula (41% vs. 13%, respectively; P < 0.5). Presence of stent or application of thrombectomy device was not associated with a statistically significant difference in re-thrombosis rate or patency period of the access after declotting procedure (rethrombosis rate: stent: 39% vs. no stent: 52%, thrombectomy device: 50% vs. no device: 34%, P > 0.05 for both; rethrombosis time: stent: 77.8 ± 105.5 days vs. no stent: 40.8 ± 43.4 days, thrombectomy device: 46.2 ± 21.6 days vs. no device: 54.3 ± 76.2 days, P > 0.05 for both). Although the presence or placement of vascular stent or application of thrombectomy device could help during initial declotting procedure, they may not be associated with patency rate and interval during the first 12-month follow-up interval.

The usefulness and feasibility of placing a clinch knot with a guidewire to achieve temporary hemostasis in arteriovenous dialysis access interventions.

To evaluate the usefulness and feasibility of using a reversible clinch knot with a guidewire in place rather than eliminating the access route during an arteriovenous hemodialysis access (AV access) intervention using the facing sheath technique. From July 2016 to June 2019, we retrospectively studied 78 sessions performed as interventional treatment for arteriovenous (AV) hemodialysis (HD) access using the "facing-sheath technique." In all sessions, all antegrade sheaths were removed while a 0.035-inch guidewire remained in place with purse-string suture and the clinch knot. Seventy-two sessions were performed in patients with thrombosed AV accesses (69 arteriovenous grafts [AVGs] and three arteriovenous fistulas [AVFs]), and six sessions were carried out to treat non-thrombosed AV accesses (four AVGs and two AVFs). We evaluated whether proper hemostasis and successful reinsertion of the sheath over the wire into the clinch knot was achieved. Clinical success was defined as achieving prompt restoration of blood flow for AV access, and the postintervention primary and secondary patency were also evaluated. In all 87 clinch knots created in 78 total sessions, proper hemostasis was achieved. All clinch knots that required reversal for additional procedures were successfully reopened (55 clinch knots in 50 sessions). The postintervention primary patency rates at 1, 3, and 6 months, and at 1 year were 77.8%, 68.9%, 55.6%, and 33.3%, respectively. The postintervention secondary patency rates at 1, 3, and 6 months, and also at 1 year were 93.3%, 91.1%, 86.7%, and 86.7%, respectively. Our AV access intervention which used a clinch knot with purse-string suture while the guidewire remained in place was both useful and feasible for maintaining temporary hemostasis.

Perioperative and long-term outcomes after percutaneous thrombectomy of arteriovenous dialysis access grafts

ObjectiveMaintenance of functional arteriovenous grafts (AVGs) for dialysis is difficult secondary to low primary patency, need for reinterventions, and limited alternative dialysis access options. We assessed our experience with percutaneous thrombectomy for treatment of occluded AVGs. MethodsWe performed a retrospective analysis of all percutaneous thrombectomies for AVGs from 2015 to 2017. These were generally performed using mechanical thrombectomy and occasional chemical tissue plasminogen activator thrombolysis, over-the-wire balloon embolectomy for inflow, and adjunctive inflow and outflow interventions as necessary. Perioperative outcomes, long-term patency, reinterventions, and need for new permanent access placement were analyzed. ResultsThere were 218 percutaneous thrombectomies performed on 86 AVGs in 77 patients. Approximately half (53.2%) of the patients were male and 68.8% were black. Mean age was 61.1 ± 13.0 years. At the time of thrombectomy, 73.8% underwent venous outflow interventions and 4.5% underwent arterial inflow interventions. Within 30 days, 24.8% of declotted grafts underwent repeated percutaneous thrombectomy, 14.3% required tunneled dialysis catheter placement, 4% developed minor access site or graft infections, and one patient underwent surgical arterial thrombectomy for arm ischemia. There were no venous thromboembolic, cardiopulmonary, or cerebrovascular complications or clinically significant pulmonary embolism. At 1 year and 3 years after percutaneous thrombectomy, freedom from repeated thrombosis was 37% and 18%, respectively, and freedom from new dialysis access placement was 66% and 51%, respectively. Overall patient survival was 82% at 3 years. ConclusionsPercutaneous thrombectomy of AVGs is safe and is associated with acceptable patency rates. This minimally invasive method extends AVG use for these high-risk patients with limited dialysis access options.

Time to thrombectomy is associated with increased risk for dialysis catheter placement.

Arteriovenous dialysis access, fistulae (AVF) or grafts (AVG), are associated with significant rates of thrombosis. Timely thrombectomy may have a significant impact on immediate and long-term access survival. However, switching to a catheter is associated with higher rates of morbidity and mortality compared with those who have an AVF or AVG. The goal of this study was to evaluate whether time to thrombectomy increases the risk for loss of dialysis access and subsequent placement of a dialysis catheter at hospital discharge, at 6 months, 12 months, and data at any time after discharge. Using retrospective data, 444 patients were identified as having undergone thrombectomy for dialysis access dysfunction between January 2008 and April 2015, with 122 hospital admissions primarily for thrombectomy. The mean age was 60.4 years, 65% were male, and 44.3% had an arteriovenous fistula as their dialysis access. The mean time to thrombectomy was 10.8 hours, and 14 patients utilised a catheter for haemodialysis as primary access upon discharge. After adjustment for prior access intervention, access type, and time to thrombectomy, the adjusted odds ratios (AOR) of a one-day delay in thrombectomy was associated with a twofold increase in requirement for catheter at discharge and at 6 months. This association remained present at any time after discharge. In this study of patients cared for within an academic health system, a single day delay in thrombectomy nearly doubled the risk of needing a dialysis catheter at hospital discharge, 6 months, or any time after discharge.

Erythrocytosis is associated with intradialytic hypotension: a case series

BackgroundFor patients with end stage renal disease undergoing hemodialysis, erythrocytosis occurs rarely. Erythrocytosis increases the risk of thrombosis, which is a common complication in hemodialysis patients. The risk of thrombosis may also be increased by hypotension. The purpose of our report is to examine the relationship between intradialytic hypotension and erythrocytosis.Case presentationWe present a series of five patients with end stage renal disease and erythrocytosis (peak hemoglobin range 15.2–18.5 g/dL). All were erythropoiesis-stimulating agent naïve and non-smokers. Prior to developing erythrocytosis, each patient developed recurring episodes of intradialytic hypotension over several months. A statistically significant inverse correlation was observed between nadir intradialytic systolic blood pressure and hemoglobin concentration. In the index case, midodrine treatment resulted in resolution of the hypotension and erythrocytosis. Most of the patients had multiple acquired renal cysts, which is a potential source of erythropoietin. Four of the five cases developed arteriovenous dialysis access or deep venous thrombosis.ConclusionsAn association between intradialytic hypotension and erythrocytosis was observed in five cases. We postulate that chronic intermittent hypotension and renal ischemia may lead to erythropoietin secretion, and this cascade could represent a newly recognized cause of secondary erythrocytosis.

Use of Drug-Coated Balloons in Dysfunctional Arteriovenous Dialysis Access Treatment: The Effect of Consecutive Treatments on Lesion Patency

PurposeA retrospective longitudinal analysis was performed to evaluate the outcome of consecutive treatments with drug-coated balloons (DCBs) in dysfunctional arteriovenous (AV) dialysis access (fistulae and grafts). Materials and MethodsFrom January 2015 to December 2017, 339 DCBs were used in 257 procedures in 165 patients with dysfunctional accesses. Of these, 38 patients had ≥ 2 procedures and were included in the analysis. A total of 112 procedures were performed with 133 devices (22 patients treated twice, 4 treated 3 times, 7 treated 4 times, 2 treated 5 times, and 3 treated 6 times). Mean balloon diameter was 8.13 mm (min-max range, 3–12 mm) and length was 63.16 mm (min-max range, 40–150 mm). Primary outcome measures were safety and effectiveness based on the noninferiority hypothesis that the second treatment would be as effective as the first regarding postintervention primary patency (PIPP). Secondary outcome measures included independent factors that may influence outcomes. ResultsMean lesion follow-up was 617 d (range, 175–1,100 d). Median PIPP durations were 216.5 d for the first intervention and 280 d for the second (P = .37; hazard ratio, 1.271; 95% confidence interval, 0.75–2.16). There was a significant difference in PIPP in favor of the second intervention when patients with only 2 interventions (22 of 38; 57.9%) were included (first intervention, 269 d; second intervention, 520 d; P = .03; hazard ratio, 2.354; 95% confidence interval, 1.087–5.098). ConclusionsThere was no significant difference in PIPP between the first and second DCB procedures. Results suggest consistency in PIPP with the use of DCBs regardless of aging AV access.

Clinical Trial End Points for Hemodialysis Vascular Access: Background, Rationale, and Definitions.

Hemodialysis vascular access is the “lifeline” for patients on hemodialysis. Unfortunately, because of its poor patency and significant complication rate, it is also the “Achilles heel” of hemodialysis. For example, the current unassisted arteriovenous fistula (AVF) maturation rate is only

Percutaneous intervention for symptomatic central vein stenosis in patients with upper limb arteriovenous dialysis access

Central venous stenosis is an important hindrance to long-term maintenance of arteriovenous access in the upper extremities in dialysis patients. AimThe present study was done to determine feasibility and clinical success of endovascular approach for the treatment of symptomatic central venous stenosis associated with significant ipsilateral limb edema in dialysis patients with vascular access in the upper limb. MethodsA database of hemodialysis patients who underwent endovascular treatment for central venous stenosis from January 2014 to January 2017 at our institute was retrospectively reviewed. Follow-up was variable. ResultsThe study included ten patients (6 men and 4 women) with a mean age of 45.2 years, who underwent thirteen interventions during a period of 3 years. The technical success rate for endovascular treatment was 100%. One patient underwent primary PTA (percutaneous transluminal angioplasty). Seven patients underwent primary PTA and stenting. Three patients underwent secondary PTA. One among these patients underwent secondary PTA twice along with fistuloplasty. One patient underwent secondary PTA with stenting. No immediate complications were encountered during the procedure. Our study shows a primary patency rate of 67% and 33% at 6 months and 12 months for PTA with stenting. Our study also shows secondary or assisted primary patency of 75% at 6 months of follow-up. ConclusionsEndovascular therapy (PTA) with or without stenting for central venous stenosis is safe, with low rates of technical failure. Multiple additional interventions are the rule and long-term patency rate is not very good.

Percutaneous intervention for restoration of patency of occluded lower limb arteriovenous dialysis access

BackgroundArteriovenous (AV) fistula thrombosis is a serious complication in patients undergoing hemodialysis, often presenting with symptoms of venous hypertension, failure to dialysis and uremic symptoms. Treatment is aimed to provide symptomatic relief and to maintain hemodialysis access site patency. AimTo describe our initial experience in the endovascular treatment of lower limb AV dialysis access (AV fistula) thrombosis and/or obstruction in patients undergoing hemodialysis. Settings and designThis was a retrospective study carried out in a tertiary care center. Study duration was 24 months. Follow-up was variable. Materials and methodsTwo patients with chronic kidney disease with stage 5 renal failure undergoing hemodialysis presented with lower limb arteriovenous dialysis access (arteriovenous fistula) failure between July 2014 and September 2016. Both the patients underwent endovascular treatment and were analyzed retrospectively. Results and conclusionBoth the patient underwent successful endovascular treatment for the failure of the lower limb AV dialysis access thrombosis and/or obstruction. One patient had minimal dye extravasation during manipulation of the guide wire, which ceased spontaneously. On follow-up, both patients maintained patency of the dialysis access and are undergoing successful hemodialysis. One patient had a recurrence of the thrombosis of the fistula at 9th month of the follow-up. Endovascular treatment was tried but we could not succeed. However, we found endovascular treatment safe and effective in treating AV fistula failures.

Definitions and End Points for Interventional Studies for Arteriovenous Dialysis Access.

This paper is part of the Clinical Trial Endpoints for Dialysis Vascular Access Project of the American Society of Nephrology Kidney Health Initiative. The purpose of this project is to promote research in vascular access by clarifying trial end points which would be best suited to inform decisions in those situations in which supportive clinical data are required. The focus of a portion of the project is directed toward arteriovenous access. There is a potential for interventional studies to be directed toward any of the events that may be associated with an arteriovenous access' evolution throughout its life cycle, which has been divided into five distinct phases. Each one of these has the potential for relatively unique problems. The first three of these correspond to three distinct stages of arteriovenous access development, each one of which has been characterized by objective direct and/or indirect criteria. These are characterized as: stage 1-patent arteriovenous access, stage 2-physiologically mature arteriovenous access, and stage 3-clinically functional arteriovenous access. Once the requirements of a stage 3-clinically functional arteriovenous access have been met, the fourth phase of its life cycle begins. This is the phase of sustained clinical use from which the arteriovenous access may move back and forth between it and the fifth phase, dysfunction. From this phase of its life cycle, the arteriovenous access requires a maintenance procedure to preserve or restore sustained clinical use. Using these definitions, clinical trial end points appropriate to the various phases that characterize the evolution of the arteriovenous access life cycle have been identified. It is anticipated that by using these definitions and potential end points, clinical trials can be designed that more closely correlate with the goals of the intervention and provide appropriate supportive data for clinical, regulatory, and coverage decisions.

Drug eluting balloons for resistant arteriovenous dialysis access stenosis.

Vascular access maintenance is vital for hemodialysis patients. Conventional balloon angioplasty is the gold standard of treatment in endovascular therapy according to published guidelines, accompanied by bare metal stents as a bail-out method. Several devices have been used so far with a view to improve patency outcomes, but only covered stents have been proposed as a valid alternative and only for venous juxta-anastomotic stenosis of arteriovenous grafts. Paclitaxel-coated balloons (PCBs) have been extensively investigated in the last few years in pilot studies with small numbers of patients in dialysis access. Results from these studies have been promising so far; however, a larger number of subjects is needed to prove outcomes. Aim of this analysis is to discuss current available studies and explore some critical aspects of PCB use in dialysis access treatment.